Recently, in broadcast stations, AV (Audio and/or Video) data as a material has been stored generally in an AV server having large capacity.
An AV server generally has RAID (Redundant Arrays of Inexpensive Disks) including a plurality of hard-disk drives, and has a plurality of input and output ports such as SDI (Serial Digital Interface) ports.
AV data sent to an AV server from outside (from a VTR in a broadcast station, a video camera of on-the-spot coverage connected to the broadcast station by the wide area network and so on) is input into one of input and output ports, and compression processing and the like is performed at the input and output port. Then, the data is sent to the RAID and is recorded in the RAID.
Further, AV data read out from the RAID and sent to one of input and ports is subject to expansion processing and the like. Then, the data is output from the input and output port and is sent to the outside (such as a computer for broadcasting, a backup computer and so on) from the AV server.
Hereupon, usually in the broadcast station, instead of transmitting a material stored in the AV server without any change when broadcasting, an edited result (namely, a complete package) of the material edited by an edit terminal (non-linear edit apparatus) is transmitted.
In related art, as a method to preview (read out) a material stored in the AV server to be edited, an input and output port of the AV server and an edit terminal are made to correspond to one by one and are connected, for example, and the material is directly previewed from the AV server through the connected input and output port (for example, refer to Japanese Patent Application No. H8-221951 published by Japan Patent Office, paragraphs 0003 to 0006 and FIG. 3).
However, in this method, because an input and output port of an AV server and an edit terminal are made to correspond to one by one and are connected, there was an inconvenience that the number of edit terminals that can preview the material stored in the AV server simultaneously in parallel is limited to the number of input and output ports of the AV server.
In a broadcast station, various kinds of and a large amount of materials stored in an AV server are often edited simultaneously in parallel in a plurality of edit terminals. In that case, it is extremely inconvenient that the number of edit terminals which can preview the material simultaneously in parallel is restricted as described above.
In addition, since AV data is dispersed and recorded in a plurality of hard disks in the RAID inside the AV server, there was such an inconvenience in this method that waiting time becomes long, when a large amount of AV data is previewed or AV data of random frames is previewed by an edit terminal,.
In editing work, after previewing by an edit terminal the whole of a certain large amount of AV data (AV data stored in an AV server after sent from a video camera of on-the-spot coverage to the broadcast station through a wide area network) as a material for edit, a portion necessary for the edit in the AV data may be determined. Further, AV data of random frames may be previewed by the edit terminal when editing (IN and OUT points are determined and modified, while viewing the video by frames and skipping frames). In those cases, it is much inconvenient that waiting time becomes long.
In light of the above, the present invention is to make a plurality of edit terminals preview a material stored in an AV server simultaneously in parallel without being restricted by the number of input and output ports of an AV server, and to make the waiting time short when an edit terminal previews a material stored in an AV server.